EP1804957A4

EP1804957A4 - Systems and methods for air purificiation using supercritical water oxidation

Info

Publication number: EP1804957A4
Application number: EP05858245A
Authority: EP
Inventors: Asdrubal Garcia-Ortiz; John Wootton; Sunggyu Lee
Original assignee: DRS Sustainment Systems Inc
Current assignee: DRS Sustainment Systems Inc
Priority date: 2004-10-22
Filing date: 2005-10-19
Publication date: 2008-10-29
Also published as: US7811537B2; WO2007001417A3; US20060088460A1; US20070217980A1; EP1804957A2; US7722823B2; WO2007001417A2

Abstract

Systems and methods using the properties of supercritical water to allow raw air including a contaminant to be combined with water and to be purified in a supercritical water oxidation (SCWO) process. A supercritical water oxidation (SCWO) air purifier will generally take in a mixture of water and raw air which includes oxygen via a pumping and mixing apparatus, put the mixture into a supercritical water reactor (SCWR), and run the resultant effluent stream through a system for separating the water from the resultant clean air and the other relatively harmless outputs of the supercritical water reactor (SCWO).

Description

Systems and Methods for Air Purification Using Supercritical Water Oxidation

BACKGROUND OF THE INVENTION

1. Field of the Invention

[0001] This disclosure relates to the field of air purification and converting air

which is unsafe for human use into air which humans can safely breathe. In particular,

this disclosure relates to the use of supercritical water oxidation to purify air.

2. Description of the Related Art

[0002] In recent years the need to segregate individuals from dangerous

substances in the air has become one of increasing interest. All human beings must breathe and the introduction of airborne agents into the air they inhale creates a

dangerous situation whereby individuals can be killed or injured and can strain medical

response capability in an area. While all environmental air contains some impurities

which can harm those breathing it, such as cold viruses and allergen molecules, modern

warfare, terrorism, technology changes, and increasing globalization have led to an

increased likelihood of larger scale contamination of air where sources of clean air can

become quickly necessary to prevent catastrophic outcomes.

[0003] The danger of a chemical, biological, or nuclear weapon being unleashed

on military forces, or on civilian centers, is a nightmare scenario for many government

organizations. Such an attack can stymie military effectiveness or bring day to day

economic activity to a grinding halt. Even without the purposeful use of nuclear, biological, or chemical weapons, the possibility of accidents involving these agents in

populated areas is also a danger and governments must be able to respond to protect the

citizenry. Still further, increases in globalization have led to increased danger of communicable disease. The recent Severe Acute Respiratory Syndrome (SARS)

outbreak and fear of other dangerous natural contagions transmitted in the air has

dramatically highlighted the need for clean air. In public forums such as stadiums, malls,

convention centers, or airplanes where a large population is breathing the same air, it is

desired to have air handling systems able to remove contaminants to prevent widespread

exposure to a contagion. Further, in the event of a catastrophic incident, governments

and emergency response agencies need to be able to quickly provide safe working

conditions for health workers and other emergency responders to contain and destroy

contaminants, whether natural or man-made, whenever and wherever may be necessary.

[0004] From the above, the need to provide safe air supplies may come upon a

population suddenly, may be preferable but not necessarily required in anticipation of a

potential release, or may be constant such as in hospitals or "clean rooms," where the

need for cleaned air is always necessary as environmental air is simply too dirty for the

specialized use to which the air is put. The need for decontamination may be known or

predicted or an increased risk may be known to be likely in some situations. Li other

situations it may come without warning.

[0005] An airborne contaminant's danger level will generally depend on

concentration. The concentration of a contaminant in the air being breathed will

generally need to be above a particular threshold or else exposure is unlikely to cause

concern. Most contaminants, if sufficiently dispersed, are not particularly dangerous.

Therefore, protection against contamination usually requires the ability to either provide

air which is known to be safe and has been stored for use during the contamination

period, or to filter air which is contaminated to remove the contamination and provide

safe air. The use of stored air is generally less effective as the storage requires specialized tanks and processes, and generally the amount of air which can be stored is

relatively small. Instead, filtration is generally used, particularly if one is attempting to

provide safe air to a group of individuals.

[0006] Filtration for harmful contaminants generally works by pulling some or all

of the contaminant from the air into a solid filter. The resulting air is then provided to

the users and generally only includes a reduced concentration of the contaminant such

that the levels are sufficiently low that the contaminant is no longer harmful or, at the worst, no longer debilitating.

[0007] To prevent introduction of contaminants later, the clean air is generally

pumped into an isolation environment which prevents introduction of unfiltered air and in which the individuals needing air are located. Smaller protective suits can provide an

isolation environment for a single person while larger isolation structures can house

multiple individual^. These isolation structures are, therefore, often the preferred method

of providing safe air. Isolation structures can have economies of scale for filtration

where larger more powerful air intake devices can be used to supply air to the structure.

Further, a structure can allow individuals therein to perform tasks as they normally would

instead of being forced to work in cumbersome individual protective suits.

[0008] Isolation structures may be permanent or may be temporary and may be

used in any environment where safe air is needed. These environments may not be

suitable for human occupancy because air is contaminated, or because air simply does not

exist. In emergency responses or military field activities on the Earth, a temporary

structure is generally preferred as it can be quickly setup anywhere when needed, and

more easily stored when not needed. Often the temporary structure is inflatable whereby

the structure can be setup in the zone of contamination and can then be filled with clean air using a portable filtration system to filter outside environmental air. The internal air

pressure then provides the shape to the structure. Once inflated, the structure will be able

to provide a safe haven for multiple people and a staging point for the use of

contamination suits to venture further into a contaminated area. Further, the structure can often be provided with more efficient heating, cooling, or other environmental

control units (ECUs) than individual protective suits can include.

[0009] FIGS. 1 and 2 provide for a first embodiment of an isolation shelter, in

particular a collective protection shelter of the type commonly used by the United States military. This structure is intended to be vehicle portable (as shown in FIG. 2) and is

usually transported on a High Mobility Multipurpose Wheeled Vehicle (HMMWV or

Humvee) (70). Once deployed, as it is in FIG. 1, the shelter (75) will have been inflated

and will comprise a self supporting isolation shelter. In the depicted embodiment, the

shelter (75) comprises two structural "buildings" connected side-by-side. There is also

an external airlock allowing access inside the shelter (75). The Humvee (70) is still

attached to the shelter (75) and generally serves as a command and control center for the

shelter (75) as well as a power source via its engine to run components in the shelter (75).

hi an embodiment, the collective protection shelter will also generally have an

environmental control unit (ECU) (not shown) and may include an external generator.

[0010] Traditionally, on both portable filtration units and in permanent structures,

filtration was performed by use of deep bed activated carbon filters or similar filters

which block particles larger than a particular size and/or that react with particles of a

particular type.

[0011] While this type of system is well understood, filters of this type all suffer

from similar drawbacks. In the first instance, changing the filter generally requires a potentially hazardous operation. As contaminants are captured by the filter to clean the

air, the filter therefore will contain a high concentration of contaminants which will often

make the filter quite toxic. These contaminants are generally still dangerous and

biologically active within the filter material. Therefore, individuals handling the filter need to be careful that they are not accidentally exposed to the contaminants or that they

do not inadvertently introduce the concentrated contaminants into an unfiltered air

stream. In many respects, the filter cleans the air while creating a dangerous solid waste

(namely the filter itself) which has to be safely disposed of to avoid later contamination.

The contaminant is not eliminated by the filtration, it is simply concentrated and captured

in a more easily disposable form.

[0012] Filters of the traditional type also have the problem of failing after a

certain amount of time. As a filter is used, the ability of the filter to successfully filter

out additional contaminants is often compromised and a dirty filter can reintroduce

contaminants to the filtered air. Further, as filters become full of contaminants the air

flow is often slowed so that motors drawing air into the structure must work harder or an

insufficient amount of air is provided. As humans generate carbon dioxide while

breathing, which is toxic to them, with insufficient clean air flow into the system, air can

rapidly become dangerous even if outside contamination is successfully removed.

[0013] Filters are also part of the significant logistic trail in both military and

civilian protection and can also be a significant expense. To date, there is no production

system that incorporates a method to measure the absorbent capacity level remaining in

filtration material. In the absence of this, protocol dictates that a filter be changed after a

predetermined number of hours in service, irrespective of whether it has filtered

contaminated air or not. This means that the filter is changed more frequently than may be needed when it is in use to prevent any unintended failure. Each change of filter

requires personnel to leave the isolation environment and to change the filter. As well as

being a tedious and dangerous task, it offers the possibility that the new filter might not

seat correctly, leaving the system potentially at risk and introducing the danger that personnel may be exposed to the contaminated air while outside the shelter.

[0014] One proposal to attempt to deal with the need to change filters is

regenerative filtration whereby the filter can be remotely cleaned. There have been

numerous different types of these proposed such as pressure swing, temperature swing,

electronic swing and hybrid systems thereof. Regenerative filtration systems, while

effective, are bulky and consume more power and, hence, are only useable in certain

applications. Further, regenerative filters provide no energy recovery but actually use

additional energy to operate as they must have power to clean. Further, the regenerative

filter cannot provide aid to the other environmental control aspects of the ECU. The

regenerative filter does not provide for heating or cooling of the air which must be

provided by the ECU. This makes the regenerative filter an expensive alternative.

Finally, a regenerative filter is still generally a standard filter, and while it can self-clean

is generally subject to the limitations on air flow and contaminant capture as a more

traditional filter. i

SUMMARY

[0015] Because of these and other problems in the art, described herein are

systems and methods for using supercritical water oxidation to purify air. These systems and methods are generally designed to be portable and to allow for relatively high speed

purifying of air .

[0016] Described herein, in an embodiment, is a method for generating breathable air comprising: having a supercritical water reactor (SCWR); providing said

SCWR with water and raw air; said raw air comprising oxygen and at least one organic

contaminant; placing said water in a supercritical state thereby dissolving said contaminant into said water; allowing said oxygen in said raw air to completely oxidize '

said contaminant creating an effluent stream comprising oxygen, water and oxidation

outputs; removing said effluent stream from said supercritical state; separating said water

from said oxidation outputs and said oxygen; and providing said oxidation outputs and

said oxygen as breathable air.

[0017] In an embodiment of the method, in said step of separating, a

concentration of at least one of said oxidation outputs is determined and said

concentration is altered prior to said step of providing.

[0018] In an embodiment of the method said raw air is air drawn from Earth's

atmosphere and may further comprise nitrogen. In another embodiment, said outputs of oxidation include at least one of: hydrogen, carbon dioxide, and carbon monoxide.

[0019] In another embodiment of the method, in said step of allowing; said

oxidation creates additional water, and said additional water is also removed in said step

of separating from other oxidation outputs and said water provided in said step of providing may be said water removed in said step of removing from a prior occurrence of

said method.

[0020] In another embodiment of the method, thermal or work energy is recovered from said effluent stream for use in said step of placing. The pressure and

temperature levels of said effluent stream may also manipulated to result in the heating or

cooling of said breathable air.

[0021] hi another embodiment of the method, said raw air further comprises an inorganic contaminant which may be precipitated from said effluent stream.

[0022] hi another embodiment, there is described herein, a system for purifying

air comprising: raw air comprising oxygen, nitrogen, and at least one organic

contaminant; water; means for taking said water and said raw air and increasing pressure

and temperature to make said water supercritical; said supercriticality and the presence of

said oxygen in said raw air forming said organic contaminant into at least one

decomposition product, said water, oxygen, nitrogen, and at least one decomposition

product comprising an effluent stream; and means for separating said water from said

effluent stream; wherein at least one of said at least one decomposition product is

selected from the group consisting of: hydrogen, carbon dioxide, carbon monoxide.

[0023] In another embodiment of the system, there may be included means for

recovery of thermal energy from said effluent stream, means for recovery of work energy

from said effluent stream, or means for reducing the temperature and pressure of said air

stream to about 294K and about 1 atm, respectively.

[0024] In a still further embodiment, there is described, a system for purifying air

comprising: feeds for raw air and input water; a supercritical water reactor (SCWR); a

condenser; a heat exchanger; a pressure exchanger; and a pressure regulator; wherein, said input water and raw air are provided to said SCWR by said feeds; wherein, said

input water, when in said SCWR, is in a supercritical state; wherein, in said SCWR, a

contaminant is removed from said raw air forming clean air; wherein, said SCWR

releases said clean air and output water as an effluent stream; wherein said heat

exchanger removes thermal energy from the said effluent stream for use in raising the

temperature of said input water and raw air; wherein said pressure exchanger removes

work energy from the said effluent stream for use in raising the pressure level of said

input water and raw air; wherein said pressure regulator adjusts the pressure level of said

clean air to a particular pressure level according to its temperature level; and wherein,

said condenser can separate said output water from said clean air

BRIEF DESCRIPTION OF THE FIGURES

[0025] FIG. 1 Provides a drawing of an embodiment of a collective protection

shelter deployed from a High Mobility Multipurpose Wheeled Vehicle (HMMWV or

Humvee).

[0026] FIG. 2 Shows the collective protection shelter of FIG. 1 stored on board a Humvee.

[0027] FIG. 3 Provides a graph showing the conditions of supercritical water.

[0028] FIG. 4 Provides a general block diagram of an embodiment of an SCWO

air purification system.

[0029] FIG. 5 Provides a graph showing various adiabatic process lines for

various inlet temperatures and pressures.

[0030] FIG. 6 Provides a graph showing inlet pressure and temperature ratios

that yield a 294 K outlet temperature.

DESCRIPTION OF PREFERRED EMBODIMENT(S)

[0031] Disclosed herein, among other things, is a supercritical water oxidation

(SCWO) system for converting raw air which may or may not contain any kind of

contaminant, whether or not harmful to human beings or whether or not present in

sufficient quantities to harm human beings, into clean air which may be safely breathed

by humans. The raw air may be supplied from any source of air but will generally be

from atmospheric air available to the system.

[0032] The term "raw air" as used herein is intended to be a general term relating

to the gaseous material generally recognized as air whose purification is desired. This

will generally be because the raw air is viewed as not clean and contains a contaminant to

be removed. However, the raw air is desired to be processed, even if such cleaning is

unnecessary. Raw air generally will comprise air of the type generally available in

Earth's atmosphere regardless of exact chemical composition and will usually include

molecules of nitrogen and oxygen. Air will also generally comprise a small percentage

of other gases, such as, but not limited to, carbon dioxide, and water vapor. The air may

further comprise any number of contaminants which will generally be solid particulates

suspended in the air or particular gases.

[0033] A contaminant, as used herein, is essentially any material mixed with,

suspended by, or in solution with the air in a sufficient concentration that breathing of the contaminated air can result in harm to human beings and specifically includes, but is not

limited to, pollutants, microorganisms, biologicals, chemicals, particulates or other

materials. One of ordinary skill in the art would recognize that some of these

contaminants are not necessarily harmful. However, contaminants will have little to no

positive effect to the human body and could result in harm, even if the risk and harm is small. Most contaminants of interest will be organic contaminants of the type forming

chemical or biological warfare agents (CBWAs) but that is not strictly required, and

I V either or both organic and inorganic contaminants can be included.

[0034] Generally, it will be presumed that the materials to be removed are either biological or chemical in nature such as microorganisms, pollens, or other materials

which have been placed in atmospheric air. It will be recognized that the contaminants in

cases where the filtration systems discussed below are most likely to be used have been

purposefully introduced by man for the purpose of terrorism or as a weapon however,

environmental contaminants such as pollen, dander, or natural microorganisms, may also

qualify as contaminants. Contaminants may be present in relatively small quantities over

a relatively large area yet still cause wide-spread contamination. The SCWO air purifier

(50) will generally be presumed to be used in conjunction with an isolation shelter, in

particular a Collective Protection Shelter as used by the U.S. Military. While this

disclosure will focus on such systems in conjunction with a Chemically and Biologically Protected Shelter System (CBPSS), it would be recognized that any isolation shelter may

be used, whether temporary or permanent and including, but not limited to: Chemically

Protected Deployable Medical Systems (CP DEPMEDS), Chemically Hardened Air

Transportable Hospitals (CHATH), Simplified Protection Equipment (SCPE), or Joint

Transportable Collective Protection Systems (JTCOPS).

[0035] To begin discussion on the removal of contaminants, it is useful to begin with an understanding of supercritical water which is used in the purification process.

[0036] FIG. 3 generally shows the region (10) where water exists in its

supercritical state. Supercritical water is recognized as having a very high solubility for

organic materials, and a very low solubility of inorganic materials. Supercritical water is used to separate out both organic and inorganic contaminants from the raw air and then

provide for clean air from the process.

[0037] FIG. 4 provides an embodiment of a block diagram showing the layout of

a supercritical water oxidation (SCWO) air purifier (50) which can be used to purify raw air into breathable air by using SCWO processes. In FIG. 4 there are generally three

broad component stages which relate to the operation of the SCWO air purifier (50).

[0038] hi the stage one components (100) raw air (515) and water (415) are input

into the system, placed under pressure and heated. In the stage two components (200), a

supercritical water reactor (SCWR) (201) takes in the pressurized and heated water and raw air mixture (615) and uses the water (415) as a solvent and the oxygen in the raw air

(515) as an oxidant to remove and/or destroy the contaminants from the raw air (515). In

the stage three components (300), the water (415) is condensed and collected and the

effluent air (315) is shuttled to the target destination. As part of the stage three

components, the effluent air (315) may be cooled using properties of the pressurized air.

Each of these component stages will now be discussed in more detail.

[0039] hi the stage one components (100) there are two chemical feeds

representing the two inputs: raw air feed (101) and input water feed (103). The raw air

feed (101) is generally arranged so as to allow raw air (515) to be obtained from a

pressurized air tank (102) from prior pumping of atmospheric air into the tank. The raw

air feed (101) generally includes a compressor (112) to compress the raw air (515) to

place it under pressure. The compressor (112) preferably pressurizes the raw air (515) to

a pressure level near the critical pressure of water (218 atm) shown in FIG. 3. The

compressor (112) may increase the pressure using any system of method known now or

later developed. The raw air (515) will also generally pass through a preheater (107) which heats the raw air (515) to a point near the critical temperature of water (374⁰C) as

also shown in FIG. 3. The raw air in this case will generally be environmental air from

the Earth's atmosphere outside of the isolation environment. The amount of air fed by air feed (101) is controlled by a flow controller (115) which will serve to insure that the

correct amount of raw air (515) is supplied to the SCWR (201) to prevent air from

passing through SCWR (201) without proper purification. The amount of raw air (515)

fed into the SCWR (201) will generally depend on the organic content ("purity") of the

raw air, and, in an embodiment, is determined during operation by the gas analysis taking place near the end of the process stream in air tester (307). At a minimum, however, the

amount of raw air (515) processed will need to be sufficient to meet the make-up air flow

required to ensure breathable air. Further, in a CBPSS, other inflatable isolation

structure, or many other isolation structures, the air flow will generally need to be

sufficient to maintain positive pressure inside the isolation structure. The raw air (515)

fed by raw air feed (101) will generally comprise a mixture of gases including nitrogen,

oxygen and a relatively small percentage of various other gases which are not

contaminants as well'as at least one contaminant to be removed. Generally, the nitrogen

will comprise about 78% of the mixture, oxygen about 21% of the mixture and the other

materials comprising about 1% of the mixture in accordance with the composition

generally accepted as Earth's atmospheric air. For the purpose of this disclosure, the

exact composition of the gases prior to purification is not important. Instead, the purpose

of the system is to produce outputs which can be combined into breathable air. In

particular, the oxygen concentration is of particular importance as is the level of carbon

dioxide. Pursuant to Occupational Safety and Hazard Administration (OSHA)

regulations, breathable air should include at least 19.5% oxygen and no more than 1% carbon dioxide. For purposes of this disclosure, effluent ("clean" or "breathable") air

(315) will therefore preferably have constituents in this range, however, any air which

can be breathed by a human for some period of time without injury is classified as clean

or breathable air. In an alternative embodiment, pure nitrogen gas or other inert gases

may also be provided on an additional feed (105) to be used to purge the system.

[0040] The input water feed (103) includes a high pressure pump (104) and a

booster pump (106) designed to feed input water (415) into the SCWO air purifier (50)

using any type of liquid feed technology known now or later developed. The pump (104)

preferably pressurizes the water (415) to a pressure level near the critical pressure of

water (218 atm) shown in FIG. 3. Before the input water (415) is provided to the SCWR

(201), it will generally pass through a preheater (107) which heats the water to a point

near the critical temperature (374° C) also shown in FIG. 3. The raw air (515) and water

(415) may be mixed prior to entering SCWR (201) as in the depicted embodiment

forming an input raw air/water mixture (615) or may be mixed in the SCWR (201) in an

alternative embodiment. Generally, there will be valves (111) at various points between

the air feed (101), water feed (103), and the SCWR (201) (and at other points in the SCWO air purifier (50)) to prevent back feed, to regulate the amount of each material

provided in the raw air/water mixture (615), and to maintain the pressure inside the

SCWR (201).

[0041] As mentioned above, the first stage components (100) may also include a

purging system. The purge system will generally comprise a nitrogen or other inert gas

feed (105) which may provide inert gas into the system under pressure. This purge can

be used to clean the system of residual materials during system shutdown or to clear out potentially dangerous air, contaminants, or other items which could get into the isolation

environment.

[0042] Input water (415), in the embodiment of FIG. 4 comprises the water (415)

output from the condenser (305) (as discussed later) which is re-fed into the system. The

input raw air/water mixture (615) may pass through the energy recovery system obtaining

heat or pressure from the effluent stream (215) prior to insertion into the SCWR (201).

In an alternative embodiment, the water (415) separated from the effluent stream (215)

may simply be allowed to retain heat and/or pressure and be directly cycled back as input water (415). Heat may also be transferred to the raw air/water mixture (615) as a by-

product from internal combustion processes or other engines or drivers which are

operating the pump (104) or other components of the SCWR air purifier (50). These

exchangers (503) and (505) may utilize any methods or means known to those of

ordinary skill in the art to exchange heat and pressure from the effluent stream (215) to

the input water/air mixture (615) to help raise the pressure and temperature levels of the

input mixture (615). In this way, the heat and pressure of the effluent stream (215) is

recycled back into the input stream (615) which helps to make the system run more

efficiently and require that less heat be generated by the heating elements (223) or

preheater (107), or less work be produced by pumps (104) and (106).

[0043] The recycling of heat and pressure and their use in the SCWO air purifier

(50) is also discussed later in conjunction with providing for cooling of the effluent air

(315) to provide for efficient air conditioning when the system is used in hot

environments. This however, occurs during the third stage components (300) and is

discussed therein. [0044] Returning to the walk through of FIG. 4, as the input mixture (615) of

water (415) and raw air (515) enters the second stage components (200) it enters into the

SCWR (201). The SCWR (201) is typically a vessel constructed according to known

high pressure design codes for Hastelloy - C276, Inconel, or other suitable material. In

an alternative embodiment, the reactor may be constructed of stainless steel. The SCWR

(201) may be either a mixing-type or continuous tubular type. As depicted in FIG. 4, the

SCWR (201) may be equipped to obtain additional heat from a heat source (223) which

heats the input water/air mixture. This includes the pre-heater (107) as well as additional heating elements (223) in the SCWR (201). Alternatively, heat exchange components

may be included in the system as discussed above.

[0045] In the SCWR (201), the supercritical water drives an oxidation reaction to

break down the organic contaminants present in the raw air into their decomposition

products such as hydrogen, water, carbon dioxide (CO₂) or carbon monoxide (CO). In

particular, the supercritical water completely dissolves all organic materials likely to be

present in the raw air. All these ingredients further will generally react completely with

the oxygen in the raw air in a homogeneous reaction phase within the SCWR (201)

resulting in creation of their decomposition products.

[0046] Unlike many other treatment processes, the process converts organic

species into water, hydrogen, carbon monoxide, carbon dioxide and other decomposition

products as opposed to simple filtration capture of the contaminant. The decomposition products of organics are all generally harmless so long as not provided in too high of a

concentration. As oxygen in the raw air is used up by the reaction and carbon dioxide is

created, there is a very slight possibility that the resultant air produced might not be

breathable. [0047] The amount of oxygen used, however, is generally very minimal (as the

contaminants are generally a very small percentage of the raw air (515)). Therefore, it is

highly unlikely that sufficient oxygen would be used up to render the air unbreathable. Further, generally only a relatively small amount of carbon dioxide is created. If

concentrations of organics are sufficiently high to prove problematic, however, oxygen

concentration in an embodiment is increased by removing other materials through the use

of air scrubbers as is understood in the art. Alternatively, the air intake may be increased

to provide more air flow. If carbon dioxide concentration is a concern, CO₂ scrubbers are

added to the effluent stream in an embodiment as discussed later. Inorganic compounds,

which are generally insoluble in the supercritical water can be precipitated out as ash or

1 salt from the SCWR. These can then be removed. A solid particulate can be removed

using any type of system known now or later discovered.

[0048] In the depicted embodiment, the SCWR (201) is monitored by a

temperature controller (221) which senses the internal temperature of the SCWR (201)

and as necessary applies additional heat input to the SCWR (201) using heating elements

(223) to maintain the temperature in the SCWR (201) near the critical temperature of

water. The pressure inside the SCWR (201) is preferably monitored by a back pressure

regulator (235) to maintain the pressure in the SCWR (201) near the critical pressure of

water. A pressure relief valve (237) may also be present in case the pressure inside the

SCWR (201) reaches dangerous levels. If such high levels are detected, pressure will

generally be released from SCWR (201) via a vent to prevent danger from explosion or

similar risks.

[0049] Once the SCWR (201) has purified the air, the resultant effluent stream

(215) which will include the clean air (315) as well as the input water (415) (which will also be very clean as a byproduct of the reaction) is passed through a forward pressure

regulating valve (211) and into the stage three components (300). Valve (211) generally

serves to control the pressure of the effluent stream entering condenser (305).

[0050] The stage three components (300) are principally related to separating water (415) and effluent air (315) in the effluent stream (215) in a useful manner. Some

or all of the water (415) may be removed depending on the desired effluent air (315). In

particular, some water (415) may purposefully not be separated to provide more humid

air to eliminate dryness for occupants. Water (415) which is separated out will generally

be stored in a storage vessel (311) until needed and then re-fed into the SCWR (201) by

the water feed (103). However, in an alternative embodiment, the water (415) may be drained off to form a potable water source due to the cleaning of the water which occurs

in the SCWR (201) simultaneous to cleaning of the raw air (515). In an embodiment,

raw water in need of processing is fed into the SCWR (201) along with the raw air (515).

The SCWR (201) then cleans both air and water simultaneously. This embodiment

provides for a powerful single system for both processes. The cleaning of water using SCWO is discussed in additional detail in United States Patent Application Serial

No. 10/840,716, the entire disclosure of which is herein incorporated by reference.

[0051] The pressure and temperature in the stage 3 components (300) will

generally be lowered to allow precipitation of the water (415) out of its supercritical

state. This pressure and temperature lowering may also be used to lower the temperature of the air to a comfortable "room temperature" without need for traditional air

conditioning setups. The precipitation of water (415) will generally be performed by a

condenser (305). The resultant liquid water is collected in the storage vessel (311) while

the remaining oxygen and nitrogen gas (and other gases and suspended particles, if present) will be sent to an air tester (307). The air tester (307) may include devices for

altering the output air (such as scrubbers to remove excess carbon dioxide or carbon monoxide) as well as devices for evaluating whether or not the output air still contains

any harmful contaminants. Presuming the air is determined to be clean, and the

percentage of various components is also not toxic, the effluent air (315) will generally

be piped into the isolation environment as clean breathable air. If there is a problem with

the effluent air (315), the effluent air (315) may be cycled back through the SCWR (201),

exhausted outside the isolation environment, or scrubbed to place the effluent air (315) in

desired form.

[0052] Control of the SCWO air purifier (50) is performed in the embodiment of

FIG. 2 by monitoring the SCWR (201) effluent air stream (315) with the air tester (307).

The air tester (307) will generally include a gas chromatograph or other suitable sensor to

determine the composition in effluent stream (215). From these results, a user can adjust

the air feed (101) and water feed (103) to control the residence time of the raw air/water

mixture in the SCWR (201). The air tester (307) may control air fed into the SCWR

(201) by means of the mass flow controller (115) using automatic control. Alternatively,

the system may be entirely regulated by a user.

[0053] As the effluent air (315) is being provided to the user, the effluent air

(315) will obviously need to be reduced from the supercritical pressure and temperature

of water which it was at in the SCWR (201) to a comfortable temperature to prevent

injury from the heat. This return can provide for an additional benefit of allowing

temperature manipulation of the air without resort to traditional air conditioning type systems. In particular, the expansion of the air from the approximately 218 atm of

pressure at the supercritical state to 2 or 1 atm which is the logical pressure that the air would be provided is a reversible adiabatic (isentropic) process. This pressure decrease

can be carried out by pressure transfer to the input raw air/water mixture. Further, the

clean air will generally automatically decrease in pressure as it is ejected into the

isolation shelter as the isolation shelter will generally be pressured at slightly above

1 atm. Simple calculation of the pressure drop from 218 atm to 1 atm indicates that the

air will in fact be placed at a temperature significantly below freezing if just being

exhausted from the SCWR (201) to the isolation shelter and would be much too cold to be provided to a human user.

[0054] To control this temperature decrease to provide for useful cooling, without

freezing, it is preferable to utilize a relationship as shown in FIG. 5. FIG. 5 provides an

indication of the temperature at which the effluent air (315) would end up in the shelter

and somewhere downstream over various air exhaust pressures for three different air

exhaust temperatures (the temperature that the air would be exhausted into the shelter).

As can be seen, if the desired shelter temperature is selected as 294 K or about 70

degrees Fahrenheit at 1 atm of pressure, levels of air exhaust temperature and pressure

for the air can be selected to obtain that result as shown by the dashed line.

[0055] The indications of this graph can then be displayed as the graph of FIG. 6.

This graph provides that for the fixed room temperature (about 70 degrees Fahrenheit)

selected, there is a curve of air exhaust temperature(s) and pressures required to reach the desired room temperature at about 1 atm pressure. The system can then utilize pressure

and heat exchange (energy recovery) as discussed in conjunction with the stage one

components (100) above to place the effluent stream (215) at a desired pressure and

temperature combination upon exhaust of the effluent air (315) into the shelter. Using

this information, the effluent air (315) will reach the desired temperature in the isolation shelter as it naturally adjusts to about 1 atm of pressure. In particular, at any point of this

line, if the effluent air (315) is exhausted into the isolation shelter, at that pressure and

temperature, the effluent air (315) will reduce to a comfortable temperature in the

isolation shelter as its pressure naturally adjusts to about 1 atm. Noticing that any point

on the line of FIG. 6 will result in effluent air (315) at 1 atm being the desired

temperature, generally a lower point on the line (lower temperature and pressure

combination) will be chosen, in this way, most of the heat and pressure from the effluent

air (315) may be removed through the heat and pressure exchangers (503) and (505) respectively allowing for recycling of these components in the system and improved

efficiency. Once the desired point of exhaust temperature and pressure is reached

(generally on or near the curve of FIG. 6), the effluent air (315) is ejected and, given its

prior state, will reduce to about one atmosphere of pressure (the pressure it is at in the

ambient environment). As the effluent air (315) adjusts to this pressure, its temperature

will continue to fall to the target temperature allowing for the system to provide air at the target temperature. If this air is used in a self contained structure, it should be clear that

the structure will therefore have air of a comfortable temperature even if air outside the

structure is not a comfortable temperature.

[0056] The embodiment of FIG. 4 does not require a particularly large setup, or

particularly complicated operation. It should be apparent that the SCWO air purifier (50)

could be assembled to be readily vehicle portable to a variety of locations. In particular,

the SCWO air purifier (50) would preferably be able to fit on a pallet such as a forklift

pallet or a 463L pallet as used by the United States Air Force. Alternatively, a scaled up

version of the SCWO air purifier (50) could be placed in an over-the-road (OTR) truck

trailer or on a pallet, crop, or flatrack utilized by Load Handling System (LHS) trucks such as the HEMTT-LHS truck used by the United States Army. Likewise, a sealed-

down version could be used for protecting the occupants inside a vehicle.

[0057] There is generally no need to provide additional water to allow the

reaction once a particular amount of water has been provided, and the water will cycle in an endless loop through the system. In an alternative embodiment as previously

discussed, the supercritical air purification technology may be combined with a

supercritical water purifier such as that discussed in United States Patent Application Serial No. 10/840,716, the entire disclosure of which is herein incorporated by reference.

In this embodiment, both raw air (515) and raw water may be provided to the system

together providing both clean air and clean water as outputs. The percentage of each may

be selected based on how much of each is needed as output (with excess being discarded

or simply serving as a surplus), or to maximize the efficiency of the reaction. Regardless

of which method is used, in the SCWR (201) whether the contaminant was originally

waterborne or airborne is irrelevant. The contaminant will be destroyed in the SCWR

(201). Therefore both clean water and clean air will be able to be removed from the

system. Depending on which of these products are to be used, one of these may be

recycled or vented or both may be sent to final end users.

[0058] SCWO air purifiers (50) can be used in a wide variety of applications and i for a wide variety of purification tasks. One such use is clearly military use. Soldiers in the field may be exposed to numerous foreign agents including foreign germs. Further,

many countries are known to have arsenals of nuclear, chemical, or biological weapons

which create dangerous air borne contaminants. Soldiers operating in these

environments can be provided with collective protection shelters in which to take refuge

in the event that such a germ or other agent is present. This can help the soldiers to weather an attack utilizing these weapons, and can also help to speed recovery from such

agents and to minimize downtime from naturally occurring contaminants.

[0059] In an alternative embodiment, while the above presumes that the air inside

the isolation shelter is clean and environmental air is contaminated, it should be apparent that the system can work in the reversed configuration. In particular, the system can also

be used for isolation of contaminated (and generally contagious) individuals. For instance, a dangerous germ agent with which some soldiers become infected may be

prevented from additional airborne contamination by placing those soldiers into a

quarantine ward. The air in this ward can be purified using an SCWO air purifier (50)

prior to returning the air to the ambient, or to providing the air to another shelter. '

Because the SCWR not only kills the germ, but will actually reduce it to decomposition

products completely destroying its structure, the germ has little chance of causing further

problems outside the isolation structure and is very effectively eliminated.

[0060] The system also has clear indications for clean rooms such as in hospitals

or in manufacturing facilities which require clean air to prevent damage to delicate

manufactured components and which can require isolation and quarantine. In these

systems, organic components will be broken down into readily identifiable gases which,

if they present a problem, can be scrubbed from the air by well known systems.

Generally, these gases will not provide a problem as they will not interact with the

components so can remain in the air. Further, inorganic materials such as dust can be

removed as ash utilizing separation systems in the SCWR and providing only gases to the

facility. This can make the facility simpler to utilize for those inside as well as actually

improving cleanliness by not simply filtering potentially dangerous or destructive agents, but by actually destroying or separating them. [0061] While the invention has been disclosed in connection with certain

preferred embodiments, this should not be taken as a limitation to all of the provided

details. Modifications and variations of the described embodiments may be made

without departing from the spirit and scope of the invention, and other embodiments should be understood to be encompassed in the present disclosure as would be

understood by those of ordinary skill in the art.

Claims

1. A method for generating breathable air comprising:

having a supercritical water reactor (SCWR);

providing said SCWR with water and raw air, said raw air comprising oxygen and at least one organic contaminant;

placing said water in a supercritical state thereby dissolving said contaminant into said water;

allowing said oxygen in said raw air to completely oxidize said contaminant

creating an effluent stream comprising oxygen, water and oxidation outputs;

removing said effluent stream from said supercritical state;

separating said water from said oxidation outputs and said oxygen; and

providing said oxidation outputs and said oxygen as breathable air.

2. The method of claim 1 wherein in said step of separating, a concentration of at

least one of said oxidation outputs is determined and said concentration is altered prior to said step of providing. <

3. The method of claim 1 wherein said raw air is air drawn from Earth's

atmosphere.

4. The method of claim 1 wherein said raw air further comprises nitrogen.

5. The method of claim 1 wherein said outputs of oxidation include at least one of:

hydrogen, carbon dioxide, and carbon monoxide.

6. The method of claim 1 wherein in said step of allowing; said oxidation creates

additional water, and said additional water is also removed in said step of

separating from other oxidation outputs.

7. The method of claim 1 wherein said water provided in said step of providing is

said water removed in said step of removing from a prior occurrence of said ^'

method.

8. The method of claim 1 wherein thermal energy is recovered from said effluent

stream for use in said step of placing.

9. The method of claim 1 wherein work energy is recovered from said effluent

stream for use in said step of placing.

10. The method of claim 1 wherein the pressure and temperature levels of said

effluent stream are manipulated to result in the heating or cooling of said

breathable air.

11. The method of claim 1 wherein said raw air further comprises an inorganic

contaminant.

12. The method of claim 11 wherein said step of allowing said inorganic contaminant

is precipitated from said effluent stream.

13. A system for purifying air comprising:

raw air comprising oxygen, nitrogen, and at least one organic contaminant;

water;

means for taking said water and said raw air and increasing pressure and

temperature to make said water supercritical; said supercriticality and the presence of

said oxygen in said raw air forming said organic contaminant into at least one

product comprising an effluent stream; and means for separating said water from said effluent stream; wherein at least one of said at least one decomposition product is selected from

the group consisting of: hydrogen, carbon dioxide, carbon monoxide.

14. The system of claim 13 further comprising:

means for recovery of thermal energy from said effluent stream.

15. The system of claim 13 /further comprising:

means for recovery of work energy from said effluent stream.

16. The system of claim 13 further comprising:

means for reducing the temperature and pressure of said air stream to about 294K and about 1 atm, respectively.

17. A system for purifying air comprising:

feeds for raw air and input water;

a supercritical water reactor (SCWR);

a condenser; a heat exchanger;

a pressure exchanger; and

a pressure regulator;

wherein, said input water and raw air are provided to said SCWR by said feeds;

wherein, said input water, when in said SCWR, is in a supercritical state;

wherein, in said SCWR, a contaminant is removed from said raw air forming

clean air;

wherein said SCWR releases said clean air and output water as an effluent

stream;

wherein said heat exchanger removes thermal energy from the said effluent

stream for use in raising the temperature of said input water and raw air; wherein said pressure exchanger removes work energy from the said effluent

stream for use in raising the pressure level of said input water and raw air;

wherein said pressure regulator adjusts the pressure level of said clean air to a

particular pressure level according to its temperature level; and

wherein said condenser can separate said output water from said clean air.